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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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ALASKAN GLACIER STUDIES
Scott Glaciers whose relationships, where crossed by the railway, are shown in the following table. This table shows clearly that the glacial streams abandon the higher points of their alluvial fans when they are built to a certain height, for at the time this railway leveling was done only one of the five fans had a stream upon its crest and that was a very small one.
TABLE SHOWING A CROSS-SECTION- OF ALLTTVIAL FANS WEST or COPPER RIVER DELTA
Position	Elevation in Feet	Position on Fan	Distance in Miles	Ascent or Descent in Feet
Eastern alluvial fan				
East Sheridan stream	15			
Small stream at Mile Post 17	49	Crest	2	+34
Near Mile Post 15	32.9		2	-16
Second alluvial fan				
Near Mile Post 14	43.9	Crest	1	+11
Main Sheridan Stream	32.9		*	-11
Near Mile Post IS	31.5		4	-I*
Third alluvial fan				
In Mile 12	42	Crest	1	+ 10*
Near Mile Post 11	28		i*	-14
Fourth alluvial fan				
Near Mile Post 10	35	Crest	*	+7
Main Scott Stream	16		ii	-19
Fifth alluvial fan				
Middle of Mile 7	20	Crest	1	+4
At Mile Post 7	15		4	-5
Middle of Mile 6	12.3		4	-*
Outlet of Eyak Lake	19.7		4	+74
This outwash gravel plain grades to fresh marsh, then to salt marsh, but in the area between the Copper River and the Sheridan Glacier streams the salt marsh extends up to the mountain base.
Relation of OvJwash Deposits to Maintenance of the Railway. Two points stand out in connection with the building of the Copper River and Northwestern Railway on the Copper River delta. One is the ease of original construction upon these smooth alluvial fans, delta plain, and valley train, aside from the necessary filling 'm swamps and on quicksands. The other is the threat of expense of maintenance of the railway.
The danger that the Sheridan Glacier might advance two and one-half miles and destroy the railway now seems practically negligible, but the danger that it may advance slightly and that the streams from it may shift and necessitate new trestles or may bury the track in places, as at Spencer Glacier on the Alaska Northern Railway,1 is an i
i Tarr, R. 8. and Martin, Lawrence, An Experiment in Controlling a Glacial Stream, Annals Aasoc Amer. Geographers, Vol. n, 1912, pp. 25-40.